Perhaps you should try some spelling variations:
thanh di » thanh doi, thanh de, thanh do
hieu van » hieu va, thien van, lieu va
su sach » so sach, vu sach
van cam » van nam, van lam, van cau
hoa hoi » khoa hoi, hoa hoc, hoa doi
cua tre » cua te, cuu tre, cua triet
tuc va » thuc va, truc va, tuc xa
ha hoi » ha noi, xa hoi, va hoi
di cua » dai cua, doi cua, de cua
ac va » tac va, bac va, mac va

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: su sach _ dang ((ha hoi) or (hoa hoi)). hieu van cam ((ac va) or (tuc va)) thanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach _ dang ((ha hoi) OR (hoa hoi)). hieu van cam ((ac va) OR (tuc va)) thanh di cua tre.
• Adding a wildcard symbol may retrieve word variants: su sach _ dang ((ha hoi) or (hoa hoi)). hieu van cam ((ac va) or (tuc va)) thanh di cua tre*.